The present invention is directed to a lance or torch for a cutting tool for burning through steel, masonry, concrete, metal-smelter plugs, and the like.
Conventional torches are generally exothermic burning rods which include a steel tube or tubes with steel wires or rods inside, wherein oxygen is circulated through the tubes and around the wires. The steel tubes and wires are ignited at one end of the tube or tubes by passing high current through the rods or by placing the end of the rods in a smoldering cardboard punk tube. The oxygen causes the smoldering tube to burn rapidly and the combustion gases and the flames coming out from the steel tube and around wires heat them sufficiently to ignite. Once ignited, the steel sustains combustion for a sufficiently long period of time until the rods are completely spent. The hot combustion products and excess oxygen flowing from the end of the burning tube and wires are sufficiently hot to burn through almost any material, including steel, stainless steel, fire bricks, and the like.
The prior art is replete with cutting torches that may be used in the open air or underwater. The examples of such torches and devices are disclosed in U.S. Pat. Nos. 3,260,076; 3,487,791; 3,500,774; 3,507,230; 3,507,231; 3,592,573; 3,658,599; 3,713,636; 3,994,666; 4,069,407; 4,114,863; 4,131,780; 4,182,947; 4,401,040; 4,416,444; 4,477,060; 4,495,848; 4,541,616; 4,559,890; 4,601,761; and 4,654,496. Additional examples are disclosed in British No. 2,151,530, Japanese No. 50 035049 and Japanese No. 78 44902.
However, conventional devices suffer with many disadvantages. For example, the torches that are used in the open air can be ignited by striking with a 50 ampere or greater arc at the tube rim, or by fanning a smoldering cardboard tube with oxygen to a white-hot flame. However, batteries required to provide the igniting current, usually of the motorcycle/automobile battery type are heavy, awkward to use, and require recharging. Additionally, igniting the cardboard punk tube in rain or under windy conditions has been observed to be difficult, and further hazardous on a scaffold or the like. Moreover, both of these igniting methods are almost useless when the torch is used underwater. The underwater objects generally have a high resistance and cannot be made part of a 50 ampere or greater ignition circuit or, conversely, a very high and dangerous voltage is necessary to overcome barnacles, slimy algae and the like.
The underwater cutting rod disclosed in U.S. Pat. Nos. 4,069,407 and 4,182,197, to Brower, uses a continuous 100 ampere or greater welding current with an oxygen-fed hollow electrode. The steady flow of current helps in underwater ignition, however, establishing the return path through the structure being cut is difficult. Moreover, the underwater use of high intensity currents poses great danger of bodily harm to the operator.
In addition to the above, although the smoldering cardboard tube or high intensity current flow through the tubes methods of igniting (generally provided by an automotive type of battery) are useful in many applications, they are not favored during rescue and emergency types of situations because of the time required to ignite the cardboard tube or handling of the bulky battery ignition system. Moreover, these ignition systems do not function properly at all during underwater cutting operations.
In view of the problems encountered, there is a need for a cutting torch which is highly reliable as to the ignition, sufficiently heat-resistant to resist flash fires, functions well under the effects of intense cold or ice-water, easily portable, ignites fast, and which does not pose a danger to the operator.